1. Field of the Invention
This invention relates to an information carrier disk housing provided with a shutter which is used in floppy disk apparatuses or the like.
2. Description of the Prior Art
FIGS. 4a and 4b, respectively, are a plan view and a side view of a conventional magnetic disk cassette 4 where a recording medium such as a magnetic disk 2 that allows storage of play back signals is rotatably housed in a cassette housing 1. The cassette housing 1 comprises an upper shell 1a and a lower shell 1b. A shutter 3 of the magnetic disk cassette 4 is usually closed by the force F.sub.A of a spring (not shown) incorporated in the cassette housing 1. The reference numeral 3a is a shutter notch.
FIG. 5a shows the above-mentioned conventional magnetic disk cassette 4 inserted halfway into a cassette holder 5 of a disk drive apparatus. The reference numeral 5b is a spring retainer which is a part of the cassette holder 5 raised up, 6 is a shutter opener arm, 6a is a shutter opener pin, 6b is a spring retainer, 7 is a shutter opener shaft, and 8 is a tension spring. The shutter opener arm 6 is rotatably linked to the cassette holder 5 by the shutter opener shaft 7 and is forced in the direction of arrow A by the tension spring 8 which is stretched between the spring retainers 5b and 6b.
FIG. 5a shows the magnetic disk cassette 4 which is being inserted into the cassette holder 5, in which the shutter notch 3a of the magnetic disk cassette 4 is going to be locked to the shutter opener pin 6a. Insertion force is further applied to the magnetic disk cassette 4 in the direction of arrow B. FIG. 5b is a perspective view of the shutter opener arm 6 and the shutter opener shaft 7.
As shown in FIG. 6, when the magnetic disk cassette 4 is pressed with an insertion force F, a rotation moment is applied to the shutter opener arm 6 by inserting the magnetic disk cassette 4 in the direction of arrow B. The rotation moment exerted by the force F is greater than the rotation moment which causes the shutter opener arm 6 to swing in the direction of arrow C, which is the sum of (1) the rotation moment exerted by the spring (not shown) incorporated in the magnetic disk cassette 4 through the force F.sub.A applied to the shutter 3 and (2) the rotation moment of the shutter opener arm 6 exerted by the force of the tension spring 8 in the direction of arrow A. As a result of inserting the cassette 4, the shutter opener arm 6 swings in the direction of arrow D around a center point P of the shutter opener shaft 7 and, at the same time, the shutter 3 of the magnetic disk cassette 4 is opened.
FIG. 7 shows the above-mentioned conventional magnetic disk cassette 4 inserted into the cassette holder 5 until the shutter 3 is fully open. At this point, the cassette holder descends to carry out chucking with a spindle shaft (not shown) and head loading.
FIG. 8 shows the above-mentioned conventional magnetic disk cassette 4 inserted into the cassette holder 5 up side down. When inserted up side down, an edge 4a of the magnetic disk cassette 4 and the shutter opener pin 6a are brought into contact with each other, first. When inserted further, the shutter opener pin 6a swings around the point P while sliding along the edge 4a of the disk cassette 4 in contact therewith, and the magnetic disk cassette 4 is further inserted along with the swing motion.
When the magnetic disk cassette 4 is inserted up side down as mentioned above, because a corner 4f of the magnetic disk cassette 4 contacts the stopper 5a of the cassette holder 5, the amount of insertion is slightly less than that in the case where the chamfered part 4e of the magnetic disk cassette 4 contacts the cassette holder stopper 5a in a normal insertion manner. Therefore, an ordinary disk drive apparatus is made in such a structure that the cassette holder lowering mechanism does not work. Consequently, the eject mechanism is not capable of ejecting the magnetic disk cassette.
However, with the above-mentioned conventional magnetic disk cassette, there has been a problem that the magnetic disk cassette is inserted to the innermost of the drive apparatus even when it is inserted up side down, and only a small portion protrudes from the panel face of the drive apparatus or the system, which makes it difficult to hold it with fingers and draw it out.